AB0733 Musculo-articular syndrome in patients with Systemic Sclerosis-polymyositis/dermatomyositis overlap syndrome.
Authors: O. Desinova, M. Starovoytova, A. Khelkovskaia-Sergeeva, L. P. Ananyeva, O. Koneva, R. Shayakhmetova, L. Garzanova, O. Ovsyannikova
Journal: Annals of the Rheumatic Diseases (2022)

Background Systemic Sclerosis-polymyositis/dermatomyositis overlap syndrome (SSc-PM/DM) occurs in 10 to 37% of cases and has great differential diagnostic difficulties. Muscle damage in SSc-PM/DM is represented by myositis with primary inflammatory and necrotic alterations in muscle fibers by type of PM/DM. Objectives To evaluate joint and muscle damage in patients with SSc-PM/DM. Methods 112 pts had idiopathic inflammatory myopathies, of which 73 pts with SSc-PM/DM (51 pts with lSSc and 22 pts with dSSc, male/female 24/49, mean age 44±14,5 years, average disease’s duration 7 (2;9) years) had the standard clinical examination, intramuscular electromyography (IM-EMG) and manual muscle testing (MMT-8). Results All pts had polyarthralgia, 40% pts - arthritis. Damage to periarticular tissues with the formation of flexion contractures was observed in 70% pts, of which 16% - contractures of large joints (knee and elbow). X-ray changes in the hands and feet (distal osteoporosis, narrowing of the joint spaces, and smoothness of the phalangettes) were observed in all pts, 13% of pts had erosions associated with osteoarthritis. There was noticed significantly frequent development of flexion contractures in pts with dSSc (p&lt;0.05) and high skin score (p&lt;0.05). Osteolysis peculiar to SSc was detected in 23.5% of pts, and soft tissue calcinosis in the area of the phalangettes, and metacarpophalangeal joints – in 32% pts. Calcifications, specifically associated with PM/DM, in the soft tissues of the shoulder and pelvic girdle, large joints were revealed in 6% pts. A direct correlation was revealed between the duration of the disease and the development of calcinosis and osteolysis (p&lt;0.05). Myalgia and proximal muscle weakness was in all pts, dysphagia – in 43% pts, and dysphonia – in 19% pts. Patients with a moderate degree of muscle weakness (MMT-8 76-115 points) prevailed and topped 41% and patients with severe disabling functional disorders (MMT-8 ≤75 points) showed 37%, of which 4% of pts were completely immobilized. In 18% of pts, PM was detected during physical and/or laboratory examination (MMT-8 ≥ 116 points). Analysis of IM-EMG of changes confirmed the presence of primary muscle inflammatory process (all patients had a decrease in motor unit action potential (MUAP) and spontaneous activity, polyphasia – in 93% of pts. A correlation was observed with laboratory and immunological signs of disease activity: between ESR and spontaneous activity (p&lt;0.02), CPK titers and polyphasia (p&lt;0.01), the presence of a-Pm-Scl and a decrease in MUAP (p&lt;0.03). Conclusion Muscular syndrome in SSc-PM/DM has clear clinical symptoms, and the underlying symptom of involvement is sharp muscle weakness with movement disorders intrinsic to PM/DM. However, such disorders do not lead to complete immobility, as in PM/DM, and they are combined with other manifestations of SSc. Articular syndrome in pts with SSc-PM/DM is mainly represented by periarticular changes, in some pts with osteolysis and calcinosis common to SSc. Disclosure of Interests None declared